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Re: Different ROMs for Lambda 8300

Posted: Wed Aug 15, 2018 7:38 am
by mrtinb
These are the ROMs for Lambda hardware I have found on Internet

Re: Different ROMs for Lambda 8300

Posted: Sat Jun 04, 2022 11:53 pm
by David G
Changes in RED (updated list)
These are the ROMs for Lambda hardware I have found on Internet

Re: Different ROMs for Lambda 8300

Posted: Mon Jun 06, 2022 6:11 pm
by mrtinb
I know the files are the same. I was trying to tell, that the same ROM had different names. Somehow I wasn’t clear.

Re: Different ROMs for Lambda 8300

Posted: Tue Sep 20, 2022 8:03 am
by frankc64
Hello!
New on this list, as I just acquired a Lambda 8300.
I need to replace the ROM in a Lambda 8300. I tried to download the Lambda 8300 ROM LAM10061.BIN, but the link seems to be broken. Does anyone here have the ROM binary.

Best
Frank

Re: Different ROMs for Lambda 8300

Posted: Tue Sep 20, 2022 8:04 pm
by mrtinb
http://web.archive.org/web/201612200322 ... M10061.BIN

As the Lambda 8300 uses masked ROM, you'll not be able to replace it with an EPROM or EEPROM without an adapter.

Re: Different ROMs for Lambda 8300

Posted: Wed Sep 21, 2022 9:51 am
by frankc64
Thanks!
Well, I guess that there is info about EPROM adaptors to be found on the web.
In the meantime I've come to suspect that my issue really has more to do with the 74LS05, as it looks like the data bus lines behave weird, while the address lines look normal.
/Frank

Re: Different ROMs for Lambda 8300

Posted: Wed Sep 21, 2022 9:53 am
by 1024MAK
It has to be said, mask ROM chips can occasionally fail, but most are fairly reliable. So it’s definitely worthwhile double checking and investigating other possible problems.

Mark

Re: Different ROMs for Lambda 8300

Posted: Wed Sep 21, 2022 10:08 am
by mrtinb
In the design of the ZX81 (which Lambda 8300 is a clone of), the ULA (glue logic IC) overrides data from for the CPU on the data bus. So the data bus signals does not look normal. However the signals are within specification to work.

This is explained in this video @6:30+ https://youtu.be/N9wEcpF-9-c

Re: Different ROMs for Lambda 8300

Posted: Wed Sep 21, 2022 10:40 am
by frankc64
Signal should be over 4V peak-to-peak, and that is the case on the address bus, but on the data bus they are less than 2V. That cannot be right.

/Frank

Re: Different ROMs for Lambda 8300

Posted: Wed Sep 21, 2022 11:26 am
by mrtinb
I'm not an expert in electronics. The construction with the 74LS05 is different from the ZX81. My guess is that the 74LS05 is used to feed the NOP instruction into the data bus from the ULA. That might be wrong, as that would conflict always on the databus, as there is no resistors between the 75LS05 and databus towards the CPU.

Image